A Pesticide Information Project of Cooperative Extension Offices of
Cornell University, Michigan State University, Oregon State University, and
University of California at Davis. Major support and funding was provided
by the USDA/Extension Service/National Agricultural Pesticide Impact
Assessment Program.

INTRODUCTION

Ziram is a carbamate, agricultural fungicide. It may be applied to the
foliage of plants, but it is also used as a soil and/or seed treatment. Ziram
is used primarily on almonds and stone fruits. It is also used as an
accelerator in rubber manufacturing, packaging materials, adhesives, and
textiles. Another use of the compound is as a bird and rodent repellent.

TOXICOLOGICAL EFFECTS

ACUTE TOXICITY

Ziram is a toxic compound which carries the signal word DANGER on its
label due to eye irritation hazard. Acute exposure among industrial and farm
workers in the former USSR caused irritation of the skin, nose, eyes and
throat (10).

The oral LD50 for ziram is 1,400 mg/kg in rats and 480 and 400 mg/kg for
mice and rabbits, respectively. Ziram has an LD50 of 100 to 150 mg/kg in
guinea pigs (2). The acute dermal LD50 for rats is greater than 6,000
mg/kg. Ziram can cause skin and mucous membrane irritation. Humans with
prolonged inhalation exposure to ziram have developed nerve and visual
disturbances (5). Ziram is corrosive to eyes and may cause irreversible eye
damage (13).

CHRONIC TOXICITY

Female rats administered relatively small amounts of ziram in their diets
(2.5 mg/kg/day) for nine months showed decreased antibody formation. Rats fed
diets containing 0.25% ziram for an unknown time period exhibited poor
growth and development (3). In a one-year feeding study with rats, no
effects were seen at the low dose of 5 mg/kg/day nor were any effects seen
in weanlings receiving 5 mg/kg in their diet for 30 days (6). At unknown
doses and duration, rats developed a peculiar hind leg grasping reaction plus
other motor changes when given ziram. Dogs also showed convulsive seizures
(4). Another study with dogs fed ziram in their diets also showed no harmful
effects for 12 months at 5 mg/kg/day (3).

Reproductive Effects

When female and male rats were given moderate doses of ziram (50 mg/kg)
for nearly two months prior to pregnancy, the rats had marked reductions in
fertility and litter size (3). The rats in this study became largely sterile
(10). A lower dose of 10 mg/kg had no effect on reproduction.

Female mice fed moderate doses (50 mg/kg/day) of ziram for 15 days
exhibited reduced fertility but no effects on fertility appeared in male mice
(2). Wasting away of the testes has been noted as a toxic effect of ziram
(4).

Teratogenic Effects

Pregnant rats administered ziram at doses of 12.5 to 100 mg/kg during the
organ forming period of pregnancy showed embryotoxic effects at doses of 25
mg/kg and greater. The compound also had a slight growth inhibiting effect on
the embryos at 100 mg/kg. Maternal toxicity was observed at all test levels
(2).

Mutagenic Effects

Numerous tests have established that ziram is mutagenic. For example,
there was an increase in the number of chromosome changes in bone-marrow
cells in mice treated with oral doses of 100 mg/kg (2).

Chromosomal changes have also been observed in workers exposed to the
compound in industrial settings for three to five years (10). The
concentration in the air averaged 1.95 mg/m3 but reached as high as 71.3 mg/m3
in some of these cases. Thus, there is a risk of mutation in humans
chronically exposed to ziram at moderate concentrations in the air.

Carcinogenic Effects

A carcinogenicity study was performed in 1983 by the National
Toxicology Program on rats and mice exposed to ziram for a 103-week period.
Under the conditions of the study, ziram was carcinogenic to male rats,
causing an increase in thyroid cancer. There was no increase in
carcinogenicity in female rats or in male mice. Female mice showed an
increase in lung tumors, but this was complicated by a virus infection making
interpretation impossible (4). There is insufficient data to make any
determinations about the risk of cancer to humans from chronic exposure to
ziram. The compound is not classifiable due to its carcinogenicity.

Organ Toxicity

The primary target organ is the thyroid as shown in a study of workers
who experienced thyroid enlargement after ziram exposure (4). Information on
the length of exposure or the dose amount was not available.

Fate in Humans and Animals

Ziram is poorly absorbed in the absence of oils. However, it may be
readily absorbed into the body in the presence of oil, including through the
skin.

Rats that had been fed low doses (30 mg/kg) of the compound for two years
had very low levels in their livers (0.03 mg). However, the zinc component of
the parent compound is stored in the body to a slightly higher degree. It was
found in bone in amounts related to the dose over a two year experiment.
Female rats had some water-soluble residues in blood, kidneys, liver, ovaries,
spleen, and thyroid 24 hours following a single oral dose (amount was not
specified) (2). Ziram that had remained unchanged in the rat was excreted in
the feces (2). This indicates that, though ziram has only a slight potential
to persist and concentrate in living tissue, the compound may be selectively
localized in the body, as are other dithiocarbamates, at sites where toxicity
may occur (2).

The highest concentrations of zinc are found in the male reproductive
system and specifically in the prostate. High concentrations also are found
in bone, liver, kidney, pancreas, and endocrine glands.

Rats that were fed low doses of ziram followed by ethyl alcohol had
higher alcohol levels in their blood stream over a four-hour period (2).

ECOLOGICAL EFFECTS

There have been no reports of ziram use resulting in adverse effects on
mammalian wildlife (7). In birds, ziram was non-toxic at 100 mg/kg (European
starlings), but the LD50 for red-wing blackbirds is 100 mg/kg. The latter
value indicates that the compound is moderately toxic to this species of bird.
Ziram is only slightly toxic to the Japanese quail. In a two-year study, the
dietary LC50 for quail was 3,346 ppm (7). In chickens, doses of 56 mg/kg
were toxic (3). Ziram has an antifertility action in laying hens. When given
to chickens in unknown amounts for unknown lengths of time, there were adverse
effects on body weight and retarded testicular development (2).

Based on data from only one species, the goldfish, the compound appears
to be moderately toxic to fish. The five hour LC50 for ziram was between 5 and
10 mg/l (11). Based on its low solubility in water, ziram should have a low
bioconcentration potential (7).

Because of the limited data available, the potential risk to wildlife and
aquatic species is currently unknown.

ENVIRONMENTAL FATE

Of the metallic dithiocarbamate fungicides, ziram is the most stable.
Ziram moderately binds to soil where it breaks down. Because the compound
is toxic to bacteria, biodegradation may be rather slow, or occurs only at
very
low concentrations.

In the environment, ziram would primarily be found in the atmosphere as
an aerosol or dust and eventually in the soil through wet and dry
precipitation. In the air and in soil, the compound is readily degraded by
ultraviolet light (2).

On plants, persistent breakdown products were formed. A significant
amount of carbon disulfide was released during the breakdown process. The
leaf surface was slightly acidic probably due to dissolved carbon dioxide (2).

There is little or no research available on the fate of the compound in
natural waters (12).

Smith, G.J. 1993. Pesticide Use and Toxicology in Relation to
Wildlife: Organophosphorus and Carbamate Compounds. United States
Department of the Interior, Fish and Wildlife Service, Resource
Publication 170.